A wireless terminal stores shared information, which is shared in authentication processing executed between the wireless terminal and an authentication device when the wireless terminal logs on to a first base station. When the connection destination is to be switched from the first base station to another base station (a second base station), a new shared key is created from the shared information which has been stored, and is sent to the authentication device via the second base station. In the case where the authentication device judges the new shared key as valid through validity judging processing with the use of the shared information, a new shared key is created to be sent from the authentication device to the second base station. An encryption key that is encrypted with this new shared key to be used in wireless communications between the wireless terminal and the second base station is received from the second base station. The encrypted encryption key is decrypted with the new shared key and, using this encryption key, the wireless terminal executes wireless communications with the second base station.